Someone from this number calls me 2-3 times per week.  The first voice message was friendly, almost as though if she sounded excited to hear from me soon, like we were old buddies and she found my number.  The same person continues to call.  She doesn't leave the purpose for her call, she doesn't say what she is calling about, she just gives her name and asks to have me call her back.  I don't answer calls from numbers I don't know, and I certainly don't call back people who are "stalking" me that I don't know.